Three-dimensional image measuring apparatus

ABSTRACT

The present invention relates to a three-dimensional image measuring apparatus comprising: an XYZ shaft transfer means mounted onto a base member; a work stage mounted to the base member, for moving a measuring object to a measuring position and thereafter supporting it and having a predetermined reference surface set at a side thereof; an image obtaining means in which it is moved toward X,Y and Z shafts by the XYZ shaft transfer means, scans a grating image by the frequency of N times to a side of the measuring object supported and fixed to the work stage, obtains the changed grating image by the measuring object by N times; a light emitting means mounted to a side of the image obtaining means for generating and emitting light with a predetermined wavelength; and a control unit which irradiates light generated from the light emitting means mounted to a side of the image obtaining means to the reference surface set the side of the work stage, receives the changed grating image obtained from the image obtaining means, thereby producing the three-dimensional image.

TECHNICAL FIELD

The present invention relates to a three-dimensional image measuringapparatus, more particularly, to a three-dimensional image measuringapparatus in which when measuring a three-dimensional image of ameasuring object, a grating image is distributed and thereafter thedistributed image is scanned alternately to a side and the other side ofthe measuring object, thereby capable of removing a shadow regiongenerated when measuring the three-dimensional image.

BACKGROUND ART

A conventional art relating to the three-dimensional image measuringapparatus is disclosed in U.S. Pat. No. 4,794,550 (filed on Oct. 15,1986, applicant: Eastman Kodak Company), which will be describedhereinafter in accordance with an accompanying drawing.

FIG. 1 is a construction view of the three-dimensional image measuringapparatus in accordance with a conventional art. As shown in FIG. 1,light generated from a light source 1 is irradiated as horizontal lightbeam 1 a having a period “d” of the grating image onto a surface 9 ofthe measuring object through a grating 2, which is moved toward “a”direction of an arrow by a grating transfer member 4, and a lens 3. Theirradiated light is scattered by angle 1 b and irradiated to a camera 7having an image sensor 6 through a lens 5 and then a sample image isobtained. The obtained sample image is processed by a computer 8 andthen a three dimensional image of the surface 3 of the measuring objectis obtained and then the obtained three dimensional image is displayedby a display device 8 b. Here, a keyboard 8 a is used for inputtingseveral information in order to measure moire pattern.

As described above, there are several disadvantages that when measuringthe three dimensional image by using the conventional moire pattern,there is a shadow region, which is impossible to measure, at anarbitrary position of the measuring object, so that the threedimensional image of the measuring object can not be measured precisely.

DISCLOSURE OF THE INVENTION

Accordingly, it is a primary object of the present invention to providea three dimensional image measuring apparatus in which when measuring athree-dimensional image of a measuring object, a grating image isdistributed and thereafter the three dimensional image changed by themeasuring object is obtained by scanning the distributed image by Ntimes to a side and the other side of the measuring object, therebyobtaining three dimensional image, so that a shadow region is removed,thereby capable of more improving measuring precision of thethree-dimensional image.

Another object of the present invention is to provide a threedimensional image measuring apparatus in which a projection portion anda 3-dimensional camera are arranged on a straight line, therebyconstructing the three dimensional image measuring apparatus morecompact.

In one aspect of the present invention, to achieve the above-describedobjects of the invention, there is provided a three-dimensional imagemeasuring apparatus comprising: an XYZ shaft transfer means mounted ontoa base member; a work stage mounted to the base member, for moving ameasuring object to a measuring position and thereafter supporting itand having a predetermined reference surface set at a side thereof; animage obtaining means in which it is moved toward X,Y and Z shafts bythe XYZ shaft transfer means, scans a grating image by the frequency ofN times to a side of the measuring object supported and fixed to thework stage, obtains the changed grating image by the measuring object byN times and alternately, scans the grating image by the frequency of Ntimes to the other side of the measuring object, obtains the changedgrating image by the measuring object by N times; a light emitting meansmounted to a side of the image obtaining means for generating andemitting light with a predetermined wavelength; and a control unitwhich, by controlling the work stage and the XYZ shaft transfer means,irradiates light generated from the light emitting means mounted to aside of the image obtaining means to the reference surface set the sideof the work stage, thereafter receives the reflected light image throughthe image obtaining means, measures a vertical distance, therebymaintaining a focus distance between the measuring object and the imageobtaining means constantly, and receives the changed grating imageobtained from the image obtaining means, thereby producing thethree-dimensional image.

The image obtaining means comprises: a projection portion which producesa grating image through a light source emitting light and a diffractiongrating, in which it is installed to a lower side of the light sourcefor receiving the light emitted from the light source and moved by agrating transfer apparatus, and penetrates the produced grating imagethrough a projection optical system installed to a lower side of thediffraction grating; a distributor, which is installed to a lower sideof the projection portion, distributes the grating image irradiatedthrough a projection optical system of the projection portion throughfirst and second mirrors transferred by a mirror transfer apparatus anddistributes the grating image through third and fourth mirrors which areinstalled to be horizontal to the left/right side of the first andsecond mirrors and first and second filters; and an imaging unit whichis installed to a lower side of the distributor, reflects horizontallythe changed grating image in which it is penetrated through the firstand second filters of the distributor and irritated to the measuringobject and then reflected, through an imaging mirror, and obtains thechanged grating image through an imaging lens and an imaging device to acamera.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become better understood with reference tothe accompanying drawings which are given only by way of illustrationand thus are not limitative of the present invention, wherein:

FIG. 1 is a construction view of a three-dimensional image measuringapparatus in accordance with the conventional art;

FIG. 2 is a perspective view illustrating the entire construction of athree-dimensional image measuring apparatus in accordance with thepresent invention;

FIGS. 3 and 4 are construction views of an image obtaining apparatusshown in FIG. 2;

FIG. 5 is an enlarged perspective view of a distributor shown in FIG. 3;

FIGS. 6 and 7 are views illustrating an embodiment of the distributorshown in FIG. 3;

FIGS. 8 and 9 are views illustrating another embodiment of thedistributor shown in FIG. 3.

BEST MODE FOR CARRYING OUT THE INVENTION

A three-dimensional image measuring apparatus in accordance withpreferred embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

FIG. 2 is a perspective view illustrating the entire construction of athree-dimensional image measuring apparatus in accordance with thepresent invention. As shown in FIG. 2, a work stage 20 is installed toan upper portion of a base member 30, an XYZ shaft transfer apparatus 10is installed to an upper portion of the work stage 20, an imageobtaining apparatus 40 is installed to the XYZ shaft transfer apparatus10 which is freely moved toward X, Y and Z shafts for measuring athree-dimension image of a measuring object 100(shown in FIG. 3), and acontrol unit 50(shown in FIG. 3) is installed to a side of the basemember 30 for entirely controlling the image obtaining apparatus 40, thework stage 20 and the XYZ shaft transfer apparatus 10.

Any one between a linear motor or a ball screw is adapted as the XYZshaft transfer apparatus 10 in order to transfer the image obtainingapparatus 40 toward X, Y and Z shafts, respectively. The work stage 20which transfers the measuring object 100 to a measuring position, asshown in FIG. 2 to FIG. 4, comprises a first guide 21, a second guide 22and a guide transfer apparatus 23.

The first guide 21 is installed to the base member 30 to be fixed andhas a predetermined reference to a side thereof. The reference surfaceis set at an arbitrary position properly from an upper portion of thefirst guide 21 or an arbitrary position of the base member 30 so thatthe image obtaining apparatus 40 may receive light. The second guide 22is installed in order to be transferred according to the size of themeasuring object 100 on the basis of the first guide 21. Fortransferring the second guide 22, the guide transfer apparatus 23 isinstalled that the first and second guides 21 and 22, respectively, arecrossed at right angles. The ball screw 23 b adapted with a motor 23 ais adapted to the guide transfer apparatus 23 and a motor 24 a and abelt 24 b are installed respectively at the insides of the first andsecond guides 21 and 22 for transferring the measuring object 100.

The control unit 50 first checks whether a focus between the measuringobject 100 and the image obtaining apparatus 40 is correct, formeasuring the measuring object 100. For this, the control unit 50generates a light having a predetermined wavelength to a predeterminedreference surface set a side of the work stage 20 by a light emittingapparatus 48 in which it is installed to a side of the image obtainingapparatus 40, that is, when seeing the image obtaining apparatus 40 fromY shaft direction, it is seen at a front side.

A laser pointer is used as the light emitting apparatus 48 forgenerating the light having a predetermined wavelength. Beforemeasurement of the measuring object 100, the control unit 50 irradiatesthe light generated from the light emitting apparatus 48 to thereference surface, receives the reflected light image through the imageobtaining apparatus 40, calculates a vertical distance between thereference surface and the image obtaining apparatus 40, and controls thedistance of Z shaft direction of the image obtaining apparatus 40 bycontrolling the XYZ shaft transfer apparatus 10 according to the result,thereby maintaining the focus distance of the measuring object 100 andthe image obtaining apparatus 40.

When the focus distance between the measuring object 100 and the imageobtaining apparatus 40 is maintained constantly, the control unit 50measures the three-dimensional image by controlling the image obtainingapparatus 40. For this, the control unit 50 first transfers the imageobtaining apparatus 40 toward X,Y and Z shafts by controlling the XYZshaft transfer apparatus 10 and then transfers it to the measuringobject 100 supported and fixed to the work stage 20. When completing thetransfer procedure, the image obtaining apparatus 40 scans a gratingimage to a side of the measuring object 100 by N times, obtains thegrating image changed by the measuring object with N times, alternatelyscans a grating image to the other side of the measuring object andobtains the grating image changed by the measuring object with N times.

The control unit 50 receives the changed grating image that it isalternately scanned to a side and the other side of the measuring object100 in the image obtaining apparatus 40 by N times and obtained, therebyproducing the three-dimensional image of the measuring object 100. Here,the control unit 50 scans alternately grating image to a side and theother side of the measuring object 100 by N times by controlling theimage obtaining apparatus 40, thereafter receives the changed gratingimage to the respective grating image and measures the three-dimensionalimage of the measuring object 100, so that more precisethree-dimensional image is obtained by removing the shadow region.

A construction of the image obtaining apparatus 40 which scansalternately to a side and the other side of the measuring object 100 andthereafter obtains the changed grating image will be described withreference to the accompanying drawings of FIGS. 3 and 4.

FIG. 3 is a construction view that the image obtaining apparatus is seenat a front surface from a Y shaft direction. FIG. 4 is a constructionview that the image obtaining apparatus is seen at a front surface froman X shaft direction. As shown in FIGS. 3 and 4, the image obtainingapparatus 40 can be constructed compactly as an outer case 40 a of theimage obtaining apparatus as depicted by a dotted line. That is, theobtaining apparatus 40 comprises a projection portion 41, a distributor44 installed to a vertical lower portion of the projection portion 41,an imaging unit 45 installed to a vertical lower portion of thedistributor 44.

The projection portion 41 produces a grating image through a lightsource 41 a emitting light and a diffraction grating 41 b which isinstalled to a lower side of the light source 41 a for receiving thelight emitted from the light source and moved by a grating transferapparatus 41 c, and penetrates the produced grating image through aprojection optical system 41 d installed to a lower side of thediffraction grating 41 b. The grating image penetrated through theprojection optical system 41 d of the projection portion 41 istransferred to the distributor 44. Here, a liquid crystal diffractiongrating can be adapted as the diffraction grating 41 b and aPZT(piezoelectric) actuator is adapted as the grating transfer apparatus41 d.

The distributor 44, which is installed to a lower side of the projectionoptical system 41 d of the projection portion 41, distributes thegrating image irradiated from the projection optical system 41 d througha grating image distributing mirror 42, which comprises first and secondmirrors 42 a and 42 b, transferred by a mirror transfer apparatus, thenpenetrates the grating image to the third and fourth mirrors 44 a and 44c which are installed to be horizontal to the left/right side of thefirst and second mirrors, thereafter filters by first and second filters44 b and 44 d which are installed to the respective lower sides of thethird and fourth mirrors 44 a and 44 c, and then scans to a side and theother side of the measuring object 100 by N times, respectively.

The grating image scanned to the measuring object 100 forms the changedgrating image by the measuring object 100 and the changed grating imageis received to the imaging unit 45. The imaging unit 45 is installed toa lower side of the distributor 44, reflects horizontally the changedgrating image, in which it is penetrated through the first and secondfilters 44 b and 44 d of the distributor 44, scanned to a side and theother side of the measuring object 100 by N times, respectively, andformed through an imaging mirror 45 a, and obtains the changed gratingimage through an imaging lens 45 b and an imaging device 45 c to acamera 45 d. Here, the camera 45 d obtains the changed grating image ofthe measuring object 100 with 2×N frames and transmits it to the controlunit 50.

The control unit 50 obtains phase values by using the respectivetransmitted changed grating image, and by using the changed gratingimage obtained from a side and the other side of the measuring object100 and removes the shadow region and saturation region by the obtainedphase value, thereby capable of measuring three-dimensional image moreprecisely.

In order to obtain a precise three-dimensional image of the measuringobject 100, in the grating image distributing mirror 42 for distributingthe grating image, as shown in FIG. 5, the center lines of each inclinedmirror surface of a first mirror 42 a and a second mirror 42 b arecrossed, contacted and formed. A grating image is scanned to a side ofthe measuring object by the first mirror 42 a by N times and thereafter,it is transferred to a Y shaft direction by the mirror transferapparatus 43 and a grating image is distributed and scanned to the otherside of the measuring object 100 by the second mirror 42 b by N times.

As an embodiment of the grating image distributing mirror 42, as shownin FIGS. 6 and 7, a triangle mirror 46 in which first and second mirrors46 a and 46 b are formed the respective inclined surfaces can beadapted. By the first mirror 46 a, the grating image is scanned to aside of the measuring object 100(shown in FIG. 3) by N times through thethird mirror 44 a and the first filter 44 b and thereafter, the trianglemirror 46 is transferred toward an X shaft direction by the mirrortransfer apparatus 43 and the grating image is distributed by the secondmirror 46 b and the distributed grating image is scanned to the otherside of the measuring object 100 through the fourth mirror 44 c and thesecond filter 44 d by N times alternately.

As another embodiment of the grating image distributing mirror 42, asshown in FIGS. 8 and 9, a rotation mirror 47 a can be adapted. By therotation mirror 47 a, the grating image is scanned to a side of themeasuring object 100 through the third mirror 44 a and the first filter44 b by N times, and thereafter as shown in FIG. 8, the rotation mirror47 a is rotated with a predetermined angle by a rotation member as agalvano mirror meter 47 b (shown in FIG. 9) and the grating image isdistributed by the fourth mirror 44 c and the second filter 44 d and thedistributed grating image is scanned to the other side of the measuringobject 100 by N times. Here, one among an air cylinder, a linear motorand a ball screw is adapted as the mirror transfer apparatus 42 a, as astraight movement member, for moving the grating image distributingmirror 42. A galvano mirror meter is used as a rotation apparatus 47 bwhich is used as a rotation member for rotating the rotation mirror 47a.

As above, when measuring the three-dimensional image of the measuringobject, the grating image is scanned to a side and the other side of themeasuring object by N times alternately, and then changed grating imageis obtained, so that the shadow region and saturation regions areremoved by using phase values obtained from a side and the other siderespectively, thereby capable of measuring three-dimensional image moreprecisely.

INDUSTRIAL APPLICABILITY

As described above, there are advantages that the grating image isscanned to a side and the other side of the measuring object by N timesalternately, and then changed grating image is obtained, so that theshadow region and saturation regions are removed by using phase valuesobtained from a side and the other side respectively, thereby capable ofmeasuring three-dimensional image more precisely, and a projectionportion, a distributor and an imaging unit are arranged on a straightline with vertical direction, thereby constructing the three dimensionalimage measuring apparatus more compact.

1. A three-dimensional image measuring apparatus comprising: an XYZshaft transfer means mounted onto a base member; a work stage mounted tothe base member, for moving a measuring object to a measuring positionand thereafter supporting it and having a predetermined referencesurface set at a side thereof; an image obtaining means in which it ismoved toward X,Y and Z shafts by the XYZ shaft transfer means, scans agrating image by the frequency of N times to a side of the measuringobject supported and fixed to the work stage, obtains the changedgrating image by the measuring object by N times and alternately, scansthe grating image by the frequency of N times to the other side of themeasuring object, obtains the changed grating image by the measuringobject by N times; a light emitting means mounted to a side of the imageobtaining means for generating and emitting light with a predeterminedwavelength; and a control unit which, by controlling the work stage andthe XYZ shaft transfer means, irradiates light generated from the lightemitting means mounted to a side of the image obtaining means to thereference surface set the side of the work stage, thereafter receivesthe reflected light image through the image obtaining means, measures avertical distance, thereby maintaining a focus distance between themeasuring object and the image obtaining means constantly, and receivesthe changed grating image obtained from the image obtaining means,thereby producing the three-dimensional image.
 2. The three-dimensionalmeasuring apparatus according to claim 1, wherein any one between alinear motor or a ball screw is adapted as the XYZ shaft transferapparatus in order to transfer the image obtaining apparatus toward X, Yand Z shafts, respectively.
 3. The three-dimensional measuring apparatusaccording to claim 1, wherein a first guide which is installed to thebase member to be fixed and has a predetermined reference to a sidethereof; a second guide which is installed in order to be transferredaccording to the size of the measuring object on the basis of the firstguide; and a guide transfer apparatus which is installed that the firstand second guides 21 and 22, respectively, are crossed at right anglesand for transferring the second guide on the basis of the first guide.4. The three-dimensional measuring apparatus according to claim 1,wherein a ball screw is adapted as the guide transfer apparatus.
 5. Thethree-dimensional measuring apparatus according to claim 1, the imageobtaining means comprises: a projection portion which produces a gratingimage through a light source emitting light and a diffraction grating,in which it is installed to a lower side of the light source forreceiving the light emitted from the light source and moved by a gratingtransfer apparatus, and penetrates the produced grating image through aprojection optical system installed to a lower side of the diffractiongrating; a distributor, which is installed to a lower side of theprojection portion, distributes the grating image irradiated through aprojection optical system of the projection portion through first andsecond mirrors transferred by a mirror transfer apparatus anddistributes the grating image through third and fourth mirrors which areinstalled to be horizontal to the left/right side of the first andsecond mirrors and first and second filters; and an imaging unit whichis installed to a lower side of the distributor, reflects horizontallythe changed grating image in which it is penetrated through the firstand second filters of the distributor and irritated to the measuringobject and then reflected, through an imaging mirror, and obtains thechanged grating image through an imaging lens and an imaging device to acamera.
 6. The three-dimensional measuring apparatus according to claim5, a liquid crystal diffraction grating can be adapted as thediffraction grating.
 7. The three-dimensional measuring apparatusaccording to claim 5, a PZT(piezoelectric) actuator is adapted as thegrating transfer apparatus of the projection portion.
 8. Thethree-dimensional measuring apparatus according to claim 5, the centerlines of each inclined mirror surface of a first mirror and a secondmirror of the distributor are crossed, contacted and formed.
 9. Thethree-dimensional measuring apparatus according to claim 5, a trianglemirror is adapted as first and second mirrors of the distributor
 10. Thethree-dimensional measuring apparatus according to claim 5 or 6, oneamong an air cylinder, a linear motor and a ball screw is adapted as themirror transfer apparatus.
 11. The three-dimensional measuring apparatusaccording to claim 5, a rotation mirror 47 a can be adapted as first andsecond mirrors of the distributor.
 12. The three-dimensional measuringapparatus according to claim 11, wherein the apparatus further comprisesa rotation apparatus for rotating the rotation mirror with apredetermined angle.
 13. The three-dimensional measuring apparatusaccording to claim 12, a galvano mirror meter is adapted as a rotationapparatus.
 14. The three-dimensional measuring apparatus according toclaim 1, a laser pointer is used as the light emitting means.